Typically, gas turbine engines include a compressor for compressing air, a combustor for mixing the compressed air with fuel and igniting the mixture, and a turbine blade assembly for producing power. Combustors often operate at high temperatures that may exceed 2,500 degrees Fahrenheit. Typical turbine combustor configurations expose turbine blade assemblies to these high temperatures. As a result, turbine blades must be made of materials capable of withstanding such high temperatures. In addition, turbine blades often contain cooling systems for prolonging the life of the blades and reducing the likelihood of failure as a result of excessive temperatures.
Typically, turbine blades are formed from a root portion and a platform at one end and an elongated portion forming a blade that extends outwardly from the platform. The blade is ordinarily composed of a tip opposite the root section, a leading edge, and a trailing edge. The inner aspects of most turbine blades typically contain an intricate maze of cooling channels forming a cooling system. The cooling channels in the blades receive air from the compressor of the turbine engine and pass the air through the blade. The cooling channels often include multiple flow paths that are designed to maintain all aspects of the turbine blade at a relatively uniform temperature. However, centrifugal forces and air flow at boundary layers often prevent some areas of the turbine blade from being adequately cooled, which results in the formation of localized hot spots. Localized hot spots, depending on their location, can reduce the useful life of a turbine blade and can damage a turbine blade to an extent necessitating replacement of the blade.
Conventional turbine blades often include a plurality of channels in the platform of a turbine blade to remove heat. As shown in FIGS. 1 and 2, some conventional platform cooling systems included film cooling orifices in the platform. During operation, the pressure of the cooling system in the turbine blade dead rim cavity is higher than the pressure on the external side of the turbine blade, which induces high leakage flow around the turbine blade attachment region and thus causes inefficient operation. Another conventional turbine blade platform cooling system, as shown in FIGS. 3 and 4, is formed from cooling channels having a high length to diameter ratio with cooling channels positioned generally parallel to an exterior surface of the turbine blade. This configuration produces unacceptably high stress levels in the platform and thus, yields a short blade useage life, which is due primarily to the large mass of turbine blade material at the front and back of the blade attachment and due to the transverse orientation of the cooling channels relative to the primary stress field. Thus, a need exists for an improved platform cooling system enabling a turbine engine to operate more efficiently.